package com.morningstar.common.utils.crypto;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.crypto.Cipher;
import java.nio.charset.StandardCharsets;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * RSA 加密/解密	工具类
 *@author yls
 */
@Slf4j
public class RSACrypto {


	/**
	 *
	 */
	private static final String RSA = "RSA";

	/**
	 * 用于封装随机产生的公钥与私钥
	 */
	private static final Map<Integer, String> keyMap = new HashMap<>();

	/**
	 * 随机生成密钥对
	 * @throws NoSuchAlgorithmException		异常信息
	 */
	private static void genKeyPair() throws NoSuchAlgorithmException {
		/*KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象*/
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(RSA);
		/*初始化密钥对生成器，密钥大小为96-1024位*/
		keyPairGen.initialize(1024,new SecureRandom());
		/*生成一个密钥对，保存在keyPair中*/
		KeyPair keyPair = keyPairGen.generateKeyPair();
		/*得到私钥*/
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		/*得到公钥*/
		String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
		/*得到私钥字符串*/
		String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
		/*将公钥和私钥保存到Map*/
		/*0表示公钥*/
		keyMap.put(0,publicKeyString);
		/*1表示私钥*/
		keyMap.put(1,privateKeyString);
	}

	/**
	 * RSA公钥加密
	 * @param str 加密字符串
	 * @param publicKey 公钥
	 * @return 密文
	 * @throws Exception 加密过程中的异常信息
	 */
	public static String encrypt(String str, String publicKey) throws Exception{
		/*base64编码的公钥*/
		byte[] decoded = Base64.decodeBase64(publicKey);
		RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance(RSA)
				.generatePublic(new X509EncodedKeySpec(decoded));
		/*RSA加密*/
		Cipher cipher = Cipher.getInstance(RSA);
		cipher.init(Cipher.ENCRYPT_MODE, pubKey);
		return Base64.encodeBase64String(cipher.doFinal(str.getBytes(StandardCharsets.UTF_8)));
	}

	/**
	 * RSA私钥解密
	 * @param str 加密字符串
	 * @param privateKey 私钥
	 * @return 铭文
	 * @throws Exception 解密过程中的异常信息
	 */
	public static String decrypt(String str, String privateKey) throws Exception{
		/*64位解码加密后的字符串*/
		byte[] inputByte = Base64.decodeBase64(str.getBytes(StandardCharsets.UTF_8));
		/*base64编码的私钥*/
		byte[] decoded = Base64.decodeBase64(privateKey);
		RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance(RSA)
				.generatePrivate(new PKCS8EncodedKeySpec(decoded));
		//RSA解密
		Cipher cipher = Cipher.getInstance(RSA);
		cipher.init(Cipher.DECRYPT_MODE, priKey);
		return new String(cipher.doFinal(inputByte));
	}

	public static void main(String[] args) throws Exception{
		genKeyPair();
		String message = "17624048713";
		log.info("随机生成的公钥为:");
		log.info(keyMap.get(0));
		log.info("随机生成的私钥为:");
		log.info(keyMap.get(1));
		String messageEn = encrypt(message,keyMap.get(0));
		log.info("加密后的字符串为: {}", messageEn);
		log.info(messageEn);
		String messageDe = decrypt(messageEn,keyMap.get(1));
		log.info("还原后的字符串为: {}", messageDe);
		log.info(messageDe);
	}
}
